655 years ago in the Nordic Bronze Age, a teenage girl was buried in a peat bog wearing a short skirt and crop top, “the best-preserved example of a style now known to be common in northern Europe during the Bronze Age.” #archaeology
#New-Mind #video on #MEMS #mechanisms. Low information content, mostly just stock footage with an inept voiceover.
#video on how the #USA sabotaged Viet Cong #weaponry in the #Vietnam war (Project Eldest Son), which was eventually leaked to the press. #history
#Great-Scott #video on soft-start #electronics design to eliminate inrush current spikes. He rigs up an impressive alumina-bodied-resistor current shunt of 200mΩ and 50W, which should be good up to 15 amps continuous duty. He finds a 10Ω green disc “ZNR1” NTC thermistor labeled “SCK 103” used in another power supply to solve this problem; it drops from 10Ω down to some 297mΩ when it warms up. But to solve the NTC thermistor cooldown problem he rigs up a relay circuit which shorts out a 3.3Ω series resistor when its IRFZ44N coil MOSFET is triggered by an RC time delay (τ = 50kΩ·10μF = 500ms). That might potentially have the same problem if the inrush-current capacitor’s discharge has a shorter time constant than the delay capacitor, but that seems unlikely.
#Leonardo da Vinci #mechanisms #video including odometer, conical ball bearing, worm-gear-driven odometer, etc.
worthless #Leonardo #mechanisms #video
#optics #precision #manufacturing #video on making things flat. Like, optically flat: 50nm peak to valley, 1nm RMS. With a “planetary polisher” or “continuous pitch polisher”, which rotates a huge pitch lap underneath a “bruiser plate,” ideally made of something like Zerodur, carrying the blank or blanks. Helpfully explains that the grooves in the pitch lap prevent aquaplaning, just like the grooves in a car tire #tread. In order to avoid having to run his machine continuously, using a many-pole #brushless motor obtained from #hoarding a washing machine, he uses a very high-viscosity pitch (100× more than normal) in a very thin layer, which he initially flattens with a granite plate for 15–20'. His pitch lap is supported on five rollerblade wheels, and he controls motor speed with a VFD. Matching the angular velocity of the lap and the blank results in constant grinding across the surface.
Bedias, #Texas is named after the local Bidai Indians, and was named Plasterville for a while after railroad official Thomas Plaster. It has "bediasite" tektites from the Chesapeake Bay bolide crater 35 million years ago.
“A 32-year-old man has been charged with murder in the strangling death of his 63-year-old mother in her Northeast Baltimore home after funeral home employees preparing the woman’s body for burial discovered signs of trauma to her head and neck that had not been apparent to law enforcement, police said Friday.
Erich Justin Kuhn was arrested Thursday and charged with first- and second-degree murder of Cathy Kuhn.
According to a statement of charges, Kuhn “provided a complete confession” of the crime, giving “details on how he attacked his mother in the television room and struck her with his bare hands,” then “strangled her for approximately 7 minutes until she stopped gurgling and finally died.”
The document says Kuhn used a telephone cord in the attack.” #news #true-crime
#video on tachometer #mechanisms for #machining
#video on magnetic encoder #precision compared to a stepper motor microstepping; the stepper has about 4° of error.
#video of Lichtenberg figures in “bottle” shapes cut out of acrylic stock on a lathe. Beautiful lightning “in a bottle”.
#bigclive #video on antiparallel green LED tape in series with a 1MΩ resistor as a replacement for a regular neon testing screwdriver